Lens heating systems and methods for an LED lighting system

ABSTRACT

Systems and methods for lighting system lens heating are described. The systems and methods include a substantially clear thermoplastic substrate; and a conductive ink or film circuit on the thermoplastic substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/182,994 filed Jun. 15, 2016, which claims the benefit ofU.S. Provisional Application No. 62/175,542, filed Jun. 15, 2015, and isincorporated herein by reference.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE TECHNOLOGY

The present technology relates to an LED lighting system. Moreparticularly, the technology relates to systems and methods forproviding an LED lighting system lens heater.

BACKGROUND

Most vehicles include some form of a vehicle headlamp and tail lamp, andother lighting systems. Lighting systems that use incandescent or HIDbulbs, for example, generate sufficient radiation, particularly in thenon-visible spectrum, so that in colder conditions, moisture in the formof condensation, rain, sleet, or snow does not form ice on the lightingsystem, which would reduce optical transmission of the lighting systemlens. Some lights that use LEDs for illumination do not generatesufficient radiation to melt snow and ice from the lighting system lens.

Therefore, what is needed are improved systems and methods thatsufficiently heat a lighting system lens to melt snow and ice to avoidreducing optical transmission of the lighting system lens.

BRIEF SUMMARY OF THE TECHNOLOGY

The present technology provides lighting system lens heating systems andmethods.

In one form, the technology provides a system for heating a lens of aLED lighting system.

In another form, the technology provides a method of heating a LEDlighting system.

In accordance with one embodiment of the technology, a system forheating the lens of a lighting system is disclosed. The system comprisesa substantially clear thermoplastic substrate; and a conductive ink orfilm circuit on the thermoplastic substrate.

In some embodiments, the heating system further includes a lens heatercircuit, with a lens heater controller operatively coupled to the lensheater circuit.

In some embodiments, the conductive ink circuit is screen printed on thethermoplastic substrate.

In some embodiments, the conductive ink circuit is a conductive silvertrace.

In some embodiments, the conductive film circuit is a conductive silvertrace.

In some embodiments, a heating output of the conductive ink circuit isregulated based upon the temperature of the conductive ink circuitutilizing a positive temperature coefficient (PTC) ink trace.

In some embodiments, the heating system further includes a dielectrictop coating on the conductive ink circuit.

In some embodiments, the conductive ink circuit has a resistance in therange of about 5 ohms to about 300 ohms.

In some embodiments, the conductive ink circuit includes traces that aregenerally equal length.

In some embodiments, the traces are connected with a busbar on anon-power connect side.

In some embodiments, the traces have a width in the range of about 0.05mm to about 1.0 mm.

In some embodiments, the conductive ink circuit produces about 1 W/in 2.

In some embodiments, the conductive ink circuit is a substantiallytransparent ink.

In some embodiments, the lens heater controller regulates the conductiveink circuit voltage to increase or decrease the power being dissipatedby the conductive ink circuit.

In some embodiments, the heating system further includes a lightingsystem lens, wherein the conductive ink circuit remains exposed on theinside of the lighting system lens.

In accordance with another embodiment of the technology, an LED lightingsystem assembly having a heated lens is disclosed. The assemblycomprises a housing, the housing including a base and a lens, the lenshaving a interior lens side and an exterior lens side; at least one LEDpositioned within the base to provide illumination through the lens; alens heater controller; a lens heater circuit operatively coupled to thelens heater controller; a substantially clear thermoplastic substratepositioned on the interior lens side; and a conductive ink or filmcircuit on the thermoplastic substrate operatively coupled to the lensheater circuit.

In some embodiments, the conductive ink on the thermoplastic substrateis placed into a pocket on a core of an injection molding tool with theconductive ink side against the core, and the conductive ink sideremains exposed on a final lighting system lens part.

In some embodiments, the conductive ink on the thermoplastic substrateis placed against a cavity side of an injection molding tool, with theconductive ink side encapsulated between the thermoplastic substrate anda final lighting system lens part.

In some embodiments, a thermoplastic resin then over molds thethermoplastic substrate, bonding only to the non-printed side of thethermoplastic substrate.

In some embodiments, the injection molding tool uses vacuum to recessand hold the thermoplastic substrate in the core.

In some embodiments, greater than 90 percent transmission rate in termsof both lumens and intensity is achieved.

In accordance with another embodiment of the technology, a method forheating a lens of a lighting system is disclosed. The method can includeapplying a conductive ink or film circuit on a substantially clearthermoplastic substrate; applying the conductive ink or film circuit onthe substantially clear thermoplastic substrate to at least one of aninterior lens side and an exterior lens side; and applying a controlledpower to the conductive ink or film circuit to heat the lens.

In some embodiments, the method further includes applying a PTC tracenear the conductive ink or film circuit; sensing the resistance of thePTC trace; and controlling the power to the conductive ink or filmcircuit based on the sensed resistance of the PTC trace.

In accordance with another embodiment of the technology, a lens heatingsystem is disclosed. The lens heating system can include a substantiallyclear thermoplastic substrate, and a conductive ink or film circuit,positioned on the thermoplastic substrate to heat the thermoplasticsubstrate. The lens heating system can further include a lens heatercircuit including a lens heater and operatively coupled to a lens heatercontroller. The controller can be configured to determine a temperatureassociated with an outer lens surface, and activate the lens heater inresponse to a determination that the temperature is less than or equalto a threshold temperature. The lens heating system can further includea spring connector including a plurality of pins, the pins configured tocouple to the conductive ink or film circuit, and the pins furtherconfigured to provide an electrical connection between the pins and theconductive ink or film circuit.

In some embodiments, the controller can be coupled to a thermistor, thethermistor configured to determine the temperature associated with theouter lens surface.

In some embodiments, the thermistor can be a negative temperaturecoefficient (NTC) thermistor.

In some embodiments, the spring connectors can be positioned at leastpartially within a lens coupled to the substantially clear thermoplasticsubstrate.

In some embodiments, the lens heater circuit can include a circuitboard, the spring connector being surface-mounted to the circuit board.

In some embodiments, the system can further include a second springconnector coupled to a second busbar of the conductive ink or filmcircuit, the spring connector coupled to a first busbar of theconductive ink or film circuit.

In accordance with another embodiment of the technology, a method forheating a lens of a lighting system is disclosed. The method can includeapplying a conductive ink or film circuit on a substantially clearthermoplastic substrate, and applying the conductive ink or film circuiton the substantially clear thermoplastic substrate to at least one of aninterior lens side and an exterior lens side. The method can furtherinclude positioning a spring connector having a plurality of pinsagainst the conductive ink or film circuit, and establishing anelectrical connection between the pins and the conductive ink or filmcircuit, and applying a controlled power to the conductive ink or filmcircuit to heat the lens.

In some embodiments, the positioning can include moving the springconnector towards the conductive ink or film circuit until the pins haveflexed a predetermined amount corresponding to establishing theelectrical connection.

In some embodiments, the method can further include receiving a valuefrom a wireless module and supplying power to the conductive ink or filmcircuit based on the value.

In some embodiments, the method can further include receiving a valuefrom a speed sensor, determining the speed value is above apredetermined threshold, and supplying, in response to determining thespeed value is below the predetermined threshold, a predetermined amountof power to the conductive ink or film circuit.

In some embodiments, the method can further include receiving a valuefrom an optical sensor, determining the optical value is below apredetermined threshold; and supplying, in response to determining theoptical value is below the predetermined threshold, a predeterminedamount of power to the conductive ink or film circuit.

In some embodiments, the method can further include positioning thespring connector at least partially within the lens coupled to thesubstantially clear thermoplastic substrate.

In accordance with another embodiment of the technology, a heatedlighting system is provided. The system can include a substantiallyclear thermoplastic substrate, a conductive ink or film circuit,positioned on the thermoplastic substrate to heat the thermoplasticsubstrate, a lens in contact with the thermoplastic substrate, and aninterconnect assembly including a plurality of spring connectors. Thespring connectors can be positioned in contact with the conductive inkor film circuit, and the interconnect assembly can be positioned atleast partially within the lens.

In some embodiments, the interconnect assembly can be configured tosupply power to the conductive ink or film circuit.

In some embodiments, the lens can be bonded to at least a portion of theinterconnect assembly and at least a portion of the thermoplasticsubstrate.

In some embodiments, the conductive ink or film circuit can bepositioned on an exterior surface of the lens.

In some embodiments, the lens can be constructed from a thermoplasticpolymer.

In accordance with another embodiment of the technology, a method formanufacturing a heated lighting system is disclosed. The method caninclude applying a conductive ink or film circuit on a substantiallyclear thermoplastic substrate, positioning the thermoplastic substratein a cavity of an injection molding tool, and positioning aninterconnect assembly in a pocket of a core of the injection moldingtool. The method can further include positioning the interconnectassembly against the thermoplastic substrate to establish an electricalconnection between the interconnect assembly and the thermoplasticsubstrate, and injecting a resin into the injection molding tool. Theinterconnect assembly can be configured to supply power to theconductive ink or film circuit via the electrical connection.

In some embodiments, the interconnect assembly can include a pluralityof pins and the positioning of the interconnect assembly against thethermoplastic substrate can include flexing the plurality of pinsagainst the conductive ink or film circuit.

In some embodiments, injecting the resin into the injection molding toolcan include overmolding at least a portion of the interconnect assemblyand at least a portion of the conductive ink or film circuit.

In some embodiments, positioning the thermoplastic substrate in thecavity can include positioning the conductive ink or film circuit toface away from the cavity.

These and other benefits may become clearer upon making a thoroughreview and study of the following detailed description. Further, whilethe embodiments discussed above can be listed as individual embodiments,it is to be understood that the above embodiments, including allelements contained therein, can be combined in whole or in part.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and features, aspects andadvantages other than those set forth above will become apparent whenconsideration is given to the following detailed description thereof.Such detailed description makes reference to the following drawings.

FIG. 1 is a perspective view of a lighting system with a lens heater inaccordance with embodiments of the present invention;

FIG. 2 is a perspective view of the lighting system of FIG. 1, with thelens removed;

FIG. 3 is a perspective view of a portion of a lens heater assembly inaccordance with embodiments of the present invention;

FIG. 4 is a schematic of a conductive ink or film circuit that can beused as a heating element in accordance with embodiments of the presentinvention;

FIG. 5 is a schematic of the conductive ink or film of FIG. 4, andattached to a lens of a light;

FIG. 6 is a table showing resistance repeatability data for variousconfigurations;

FIG. 7 is a view showing a thermal image of a lighting system with thelens heater assembly energized, in accordance with embodiments of thepresent invention;

FIG. 8 is a view showing a thermal image of just the lens of a lightingsystem with the lens heater assembly energized, in accordance withembodiments of the present invention;

FIG. 9 is a perspective view of a lighting system with approximately 2mm of ice buildup;

FIG. 10 is a perspective view of the lighting system of FIG. 9 with thelens heater circuit energized and with the ice substantially clear fromthe optical area;

FIG. 11 is a view showing an alternative embodiment having a lens heatercircuit made up of traces with generally unequal trace lengths;

FIG. 12 is a view showing an alternative embodiment having a lens heatercircuit made up of traces with generally equal trace lengths;

FIG. 13 is a graph showing a key characteristic of PTC inks;

FIG. 14 is a schematic view showing an embodiment of a lens heaterassembly layout (without the lens heater circuit) and with the PTC tracefor temperature sensing;

FIG. 15 is an enlarged view of a portion of FIG. 14 showing the PTCtrace;

FIG. 16 is a schematic view showing a positioning of the ink and screenprinted substrate in an injection molding tool to produce a lightingsystem lens with a lens heater in accordance with embodiments of thepresent invention;

FIG. 17 is an enlarged view of a portion of FIG. 16;

FIG. 18 is a schematic view showing an alternative positioning of theink and screen printed substrate in an injection molding tool to producea lighting system lens with a lens heater in accordance with embodimentsof the present invention;

FIG. 19 is an enlarged view of a portion of FIG. 18;

FIG. 20 is a table showing the optical impact of the lens heater traceson low beam illumination and hi beam illumination; and

FIG. 21 is an exploded perspective view of an alternative embodiment ofa lighting system with a lens heater in accordance with embodiments ofthe present invention.

FIG. 22 is a perspective view of an alternative embodiment of a lightingsystem.

FIG. 23 is a front view of the lighting system of FIG. 22.

FIG. 24 is an exploded view of the lighting system of FIG. 22.

FIG. 25 is an exploded view of a lens, an interconnect assembly and athermoplastic substrate of the lighting system of FIG. 22.

FIG. 26 is a perspective view the interconnect assembly of FIG. 22.

FIG. 27 is another perspective view the interconnect assembly of FIG.22.

FIG. 28 is an exploded view of the interconnect assembly and thethermoplastic substrate of the lighting system of FIG. 22.

FIG. 29 is another view of the interconnect assembly and thethermoplastic substrate isolated from other components of the lightingsystem of FIG. 22.

FIG. 30 is a cross sectional view of the lens, the interconnect assemblyand the thermoplastic substrate of the lighting system of FIG. 22.

FIG. 31 shows an example process for manufacturing a lens bonded to atleast a portion of a thermoplastic substrate and an interconnectassembly, according to some embodiments.

FIG. 32 shows a circuit diagram of a driver circuit and a heatercircuit, according to some embodiments.

FIG. 33 shows an exemplary box diagram for an exemplary heater controlsystem of a lighting system, according to some embodiments.

FIG. 34 is a perspective view of an alternative embodiment of a lightingsystem.

FIG. 35 is a front view of the lighting system of FIG. 34.

FIG. 36 is a perspective view of an alternative embodiment of a lightingsystem.

FIG. 37 is an exploded view of the lighting system of FIG. 36.

FIG. 38 is a front view of the lighting system of FIG. 36.

FIG. 39 is a view of an interconnect assembly, a lens, and athermoplastic substrate of the lighting system of FIG. 36.

FIG. 40 is a perspective view of an alternative embodiment of a lightingsystem.

FIG. 41 is a front view of the lighting system of FIG. 40.

FIG. 42 is a view of an interconnect assembly, a lens, and athermoplastic substrate of the lighting system of FIG. 40.

FIG. 43 is a view of an interconnect assembly, a lens, and athermoplastic substrate of the lighting system of FIG. 40.

FIG. 44 is a view of the interconnect assembly and the thermoplasticsubstrate of the lighting system of FIG. 40.

FIG. 45 is another view of the interconnect assembly and thethermoplastic substrate of the lighting system of FIG. 40.

FIG. 46 is yet another view of the interconnect assembly and thethermoplastic substrate of the lighting system of FIG. 40.

FIG. 47 is a perspective view of an alternative embodiment of a lightingsystem.

FIG. 48 is a front view of the lighting system of FIG. 47.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions and/or relative positioningof some of the elements in the figures may be exaggerated relative toother elements to help to improve understanding of various embodimentsof the present invention. Also, common but well-understood elements thatare useful or necessary in a commercially feasible embodiment are oftennot depicted in order to facilitate a less obstructed view of thesevarious embodiments. It will further be appreciated that certain actionsand/or steps may be described or depicted in a particular order ofoccurrence while those skilled in the art will understand that suchspecificity with respect to sequence is not actually required. It willalso be understood that the terms and expressions used herein have theordinary technical meaning as is accorded to such terms and expressionsby persons skilled in the technical field as set forth above, exceptwhere different specific meanings have otherwise been set forth herein.

DETAILED DESCRIPTION OF THE TECHNOLOGY

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe use the phraseology and terminology used herein is for the purposeof description and should not be regarded as limiting. Furthermore, theuse of “right”, “left”, “front”, “back”, “upper”, “lower”, “above”,“below”, “top”, or “bottom” and variations thereof herein is for thepurpose of description and should not be regarded as limiting. The useof “including,” “comprising,” or “having” and variations thereof hereinis meant to encompass the items listed thereafter and equivalentsthereof as well as additional items. Unless specified or limitedotherwise, the terms “mounted,” “connected,” “supported,” and “coupled”and variations thereof are used broadly and encompass both direct andindirect mountings, connections, supports, and couplings. Further,“connected” and “coupled” are not restricted to physical or mechanicalconnections or couplings.

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

A high optical transmission lens heater is needed to prevent icing ofcertain LED lighting systems. Referring to FIGS. 1 and 2, in someembodiments, an over molded screen printed conductive circuit can beused as the heating element for a lighting system 20. The lightingsystem 20 can include a housing 24, with the housing including a base 28and a lens 32. The lens 32 has an interior lens side 36 and an exteriorlens side 40. At least one LED 44 can be positioned within the base 28to provide illumination through the lens 32. A lens heater assembly 70can include a lens heater controller 48, with a lens heater circuit 52operatively coupled to the lens heater controller 48. In someembodiments, a substantially clear thermoplastic substrate 60 can bepositioned on the interior lens side 36 of the lens, and a conductiveink or film circuit 66 can be positioned on the thermoplastic substrate66 and can be operatively coupled to the lens heater circuit 52. In someembodiments, a reflector 68 can be included to guide illumination fromthe one or more LEDs 44.

In some embodiments, the heating output of the heating element can beregulated based upon the temperature of the heating element tracesutilizing a positive temperature coefficient (PTC) ink trace.

FIG. 3 shows an embodiment of the lens heater circuit 52. The lensheater circuit 52 can be coupled to the lens 32, or can be positionedwithin the base 28. When the lens heater circuit is coupled to the lens32, as shown in FIG. 3, power wires 56 (see FIG. 2) can extend from thebase and couple to a connector 54 on the lens heater circuit. In someembodiments, a conductive element 58 can be used to provide power fromthe lens heater circuit 52 to the conductive ink circuit 66. Theconductive element can be a spring or a wire, for example.

FIGS. 4 and 5 show embodiments of a conductive ink or film circuit 66that can be used as the heating element. It is to be appreciated thatthe terms ink and film are used interchangeably herein. In someembodiments, the conductive film 66 is a conductive silver trace. It isto be appreciated that other resistive elements can be used for theconductive film. FIG. 4 shows the conductive silver traces that havebeen screen printed on the clear substrate films 60. In some embodimentsthe substrate 60 can be a thermoplastic polymer. In some embodiments,the substrate 60 can be a polycarbonate substrate. Again, othersubstrate materials can be used. FIG. 5 shows the conductive film 66 onthe substrate 60 preliminarily attached to the lighting system lens 32for testing. The substrate 60 could be any clear or substantially clearsubstrate film. Opaque substrate can also be used.

An embodiment of the lens heater assembly 70 was tested using multipletypes of inks with and without a dielectric top coating. The lens heaterassembly 70 was also tested on multiple substrate thicknesses. FIG. 6shows resistance repeatability data for the various configurations. Insome embodiments, the lens heater circuit 52 can have a resistance inthe range of about 5 ohms to about 300 ohms, depending upon theapplication. Some 12-24V lighting system applications may be around 30ohms, or more or less. Other voltages and resistances are contemplated.

A version of the lens heater assembly 70 was taped to an existing moldedouter lens 32 and thermal testing was completed on the stand alone lens32 as well as the lamp assembly. FIGS. 7 and 8 show thermal images ofthe lighting system assembly 20 (FIG. 7) and just the lens 32 (FIG. 8)and with the lens heater assembly energized. In the figures, temperatureis represented by 72 being hot, 74 being warm, 76 being cool, and 78being cold. It is to be appreciated that these descriptions of hot,warm, cool, and cold are relative terms, and are only intended to show agradient of temperature ranges that can be produced by the lightingsystem 20.

FIG. 9 shows a lighting system 20 in a cooling chamber saturated at −20C with approximately 2 mm of ice buildup 80. FIG. 10 then shows the samelighting system 20 with LEDs 44 energized, e.g., low beam and hi beam,along with the lens heater circuit 52 energized and dissipatingapproximately 18 watts. Ice 80 was substantially cleared from theoptical area 84 in several minutes. The cooling chamber remained at −20C with considerable convective airflow.

FIG. 11 shows one embodiment having a lens heater circuit 52 made up oftraces 88 with unequal trace lengths. This arrangement creatednon-uniform heating of the traces 88. This arrangement may be useful forcertain applications. Slightly warmer heating in the center 92 can beseen as compared to the edges 96. FIG. 12 shows an additional embodimentwith generally equal length traces 88. A more uniform heating can beseen. The traces can be connected with a busbar 100 on the non-powerconnect end 104 to allow for equal trace lengths, which can also beuseful in certain applications. In the figures, temperature isrepresented by 72 being hot, 74 being warm, 76 being cool, and 78 beingcold. It is to be appreciated that these descriptions of hot, warm,cool, and cold are relative terms, and are only intended to show agradient of temperature ranges that can be produced by the lightingsystem 20.

In some embodiments, a silver based screen printable ink can be used asthe lens heater traces 88. Silver allows for low resistance traces evenwhen the traces are very thin. In some embodiments, the ink can beprinted at a thickness between about 5-15 micrometers (could vary moreor less than this in other embodiments). Other conductive inks could beutilized provided they can meet the overall resistance requirements forvarious applications.

In some embodiments, the width of the lens heater traces used as heatingelements can be about 0.35 mm. This can vary from about 0.05 mm to about1.0 mm on various embodiments. The lens heater traces can be spaced atapproximately 8 mm to provide uniform heating of the entire lenssurface. This distance can be increased to approximately 15 mm and stillbe effective, and can be reduced for other applications. It is to beappreciated that other dimensions are possible.

In some embodiments, the overall resistance of the lens heater circuit52 can be about 30 ohms. In other embodiments, this can vary from about5 ohms to about 300 ohms in various designs.

Through testing, it has been found that approximately 1 W/in 2 appliedto the internal surface of a thermoplastic polymer outer lens 32 can bean adequate amount of power per optical area of an LED lamp toeffectively de-ice. In other embodiments, this could be increased to 2W/in 2 or more on other designs. Some embodiments of the lighting system20 can be designed around a dissipation of about 18 Watts. It is to beappreciated that other dissipations are possible.

In other embodiments, the lens heater portion may not necessarily needto be opaque traces of a conductive ink. The lens heater traces 88 couldbe a substantially transparent ink, for example, (e.g., approximately 85percent, or more or less, transmission), that can cover a portion or theentire surface of the heater substrate 60. This transparent ink may alsoinclude a more conductive ink screen over it to create busbars and inputpower connection points. Non-limiting examples of clear conductive inkinclude those based on carbon or graphite nanotechnology, silver microor nano structures, as well as indium tin oxide, silver or copper microfoil grids.

As mentioned above, PTC ink traces 108 may also be incorporated into thelens heater circuit 52. FIG. 13 is a graph that shows a keycharacteristic of PTC inks. As the temperature increases so does theresistance of the PTC ink. At a certain predetermined temperature, theincrease in resistance can become exponential. In some embodiments, aPTC trace 108 can be located near one or more of the lens heater traces88. In some embodiments, when the lens heater trace 88 approaches about40 C-60 C, the PTC trace resistance can go to infinity. A lens heatercontroller 48 can recognize this change in resistance and vary voltagesupplied to the lens heater circuit 52 to keep the lens heater trace 88at or near about 40 C during operation. In some embodiments, a 40 C PTCink offered by Henkel AG & Company, KGaA, can be used. PTC inks fromDupont and others can also be used.

FIG. 14 shows an embodiment of a lens heater assembly 70 layout (withoutthe lens heater circuit 52) and with the PTC trace 108 for temperaturesensing. With the opposing busbar 120, in some embodiments, most or alltraces can be substantially equal length and can heat uniformly. Therecan be multiple connection points (could have more than one connectionper power busbar 116 to reduce current traveling through a singlepoint). The top connection point 128 and bottom connection point 132support the potential across the lens heater traces 88. The top 128 andcenter 136 connection points allow for measurement of resistance acrossthe PTC trace 108 serving as a thermistor.

FIG. 15 shows the PTC trace 108 enlarged. Since the PTC trace can runalongside the lens heater trace 88, it can nearly have the sametemperature as the lens heater trace. As the lens heater traceapproaches 40 C, the PTC trace's resistance can begin to increaseexponentially. At some point on the exponential curve 144 (see FIG. 13),the lens heater controller 48 can begin to regulate the lens heatervoltage and thus decrease the power being dissipated by the lens heatercircuit 52.

FIG. 16 shows the positioning of the ink 66 and screen printed substrate60 in an injection molding tool 146 to produce a lighting system lenswith a lens heater. FIG. 17 is a close-up view. The clear substrate 60with a screen printed conductive ink 66 pattern can be placed into apocket on the core 148 with the ink side against the core. In thisarrangement, the exposed ink side can remain exposed on the finallighting system lens part 32. Molten resin can then over mold thesubstrate 60, bonding only to the non-printed side of the clearsubstrate 60. In some embodiments, various types of thermoplasticpolymers, such as polycarbonate materials, can be utilized as theinjected resin 152 for the lens 32. It is to be appreciated that otherassembly arrangements are contemplated where the ink 66 side remainsexposed on the final lighting system lens part 32.

FIG. 18 shows an alternative arrangement for the positioning of the ink66 and screen printed substrate 60 in an injection molding tool 146 toproduce a lighting system lens with a lens heater. FIG. 19 is a close-upview. The ink 66 can be encapsulated as well as with the clear substrate60 placed against the cavity side 156 of the tool.

Testing showed successful over molding of the thermoplastic filmsubstrate screen printed lens heater traces 88. Both were taped to thecore of the injection molding tool to prevent material from pushing thelabel up against the cavity 156. The tool 146 can be modified to recessthe thermoplastic substrate 60 and conductive ink 66 into the core 148and to hold it there with a vacuum. In some embodiments, the conductiveink 66 can be exposed on the interior side 36 of the lens 32.

FIG. 20 includes a table that shows the optical impact of the lensheater traces 88 on low beam illumination and hi beam illumination. Theimpact of the lens heater traces 88 on illumination output is onlyminimal, and may be non-perceivable, and can be reduced further throughthinner lens heater traces. In some embodiments, greater than 90 percenttransmission rate in terms of both lumens and intensity can be achieved.This can be varied depending on the lighting system application byvarying a thickness of the lens heater traces and the material used forthe conductive traces 66 and the substrate 60.

FIG. 21 shows an alternative embodiment of a lighting system 200. Thelighting system 200 can include a base 204 and a lens 208. The lens 208has an interior lens side 216 and an exterior lens side 212. At leastone LED 220 can be positioned within the base 204 to provideillumination through the lens 208. A lens heater assembly 222 caninclude a lens heater controller 224, with a lens heater circuit 228operatively coupled to the lens heater controller 224. In someembodiments, a substantially clear thermoplastic substrate 232 can bepositioned on the interior lens side 216 of the lens, and a conductiveink or film circuit 236 can be positioned on the thermoplastic substrate232 and can be operatively coupled to the lens heater circuit 228. Insome embodiments, a reflector 240 can be included to guide illuminationfrom the one or more LEDs 220. In some embodiments, the lens heatercircuit 228 can include one or more contacts 248 to allow for thetransmission of power from the lens heater circuit 228 to the conductiveink circuit 236. A conductive element 244, e.g., a spring or a wire, canbe positioned to electrically couple the contact 248 with a contact 252on the conductive ink circuit 236. In some embodiments, the conductiveelement 244 can pass through the reflector 240 to provide the power fromthe lens heater circuit 228 to the conductive ink circuit 236.

Referring to FIGS. 22-29, components of a lighting system 256 are shownaccording to embodiments of the present disclosure. The lighting system256 can include a base 260 and a lens 264. As shown, the lens 264 has aninterior lens side 268 and an exterior lens side 272. According to someembodiments, at least one LED 276 can be positioned within the base 260to provide illumination through the lens 264. A lighting assembly 280(e.g., as shown in FIG. 24) can include a controller and/or regulatorycircuitry coupled to the at least one LED 276 to control power suppliedto the at least one LED 276. Additionally, the lighting assembly 280 maybe coupled to a interconnect assembly 284 (e.g., as shown in FIG. 25) inorder to control power supplied to the interconnect assembly 284 and/orcommunication between the lighting assembly 280 and the interconnectassembly 284. The interconnect assembly 284 can be used to provide heatto a thermoplastic substrate 288, as will be explained below.

In some embodiments, the thermoplastic substrate 288 (e.g., as shown inFIG. 25) can be made from certain materials including substantiallyclear thermoplastic. A conductive ink circuit 292, which may also bereferred to as a conductive film circuit, can be positioned on thethermoplastic substrate 288 and coupled to the interconnect assembly284, details of which will be explained below. In some embodiments, theconductive ink circuit 292 can include conductive silver deposited onthe thermoplastic substrate 288 using a known technique such as screenprinting. The conductive ink circuit 292 can provide heat whenappropriate electrical power is provided to the conductive ink circuit292.

In some embodiments, the conductive ink circuit 292 can be positioned onan inner thermoplastic substrate surface 296 (e.g., as shown in FIG.25). Additionally, the inner thermoplastic substrate surface 296 can bepositioned over the lens 264. An outer thermoplastic substrate surface300 can be exposed to an environment (including, for example, lowtemperatures) surrounding the lighting system 256. In some embodiments,the conductive ink circuit 292 may efficiently prevent ice from formingon the lighting system 256 when the thermoplastic substrate 288 ispositioned on top of (e.g., over) the lens 264 due to the relativethickness of the thermoplastic substrate 288 as compared to the lens264. The smaller thickness of the thermoplastic substrate can allow heatto be more efficiently transferred to the outermost surface of thelighting system 256, and may prevent ice from building up andpotentially occluding illumination from the at least one LED 276.

In some embodiments, the interconnect assembly 284 can be coupled to theconductive ink circuit 292 in order to supply power to the conductiveink circuit 292. In shown by FIG. 26, the interconnect assembly 284 caninclude spring connectors 304 coupled to a circuit board 308, which canbe a printed circuit board. Portions of the conductive ink circuit 292may act as busbars to allow for efficient power transfer from the springconnectors 304 to the conductive ink circuit 292. In some embodiments,the spring connectors 304 can be included for power and ground terminalsof the conductive ink circuit 292. Each spring connector 304 can haveany number of pins 312, such as two pins, three pins, four pins, or fivepins. Additional pins can allow for higher current carrying capacity dueto a larger connection area on the conductive ink circuit 292. In someembodiments, the spring connectors 304 can be battery-type connectors,such as the 9155-200 battery connector offered by AVX®. The pins 312 canbe flexed and/or depressed when the interconnect assembly 284 is pressedagainst the thermoplastic substrate 288. The pins 312 may be configuredto be biased to an outermost position and require progressivelyincreasing force to be further flexed and/or depressed as theinterconnect assembly 284 is pressed against the thermoplastic substrate288. The pins 312 and the interconnect assembly 284 can then be held inplace as injection molded around the interconnect assembly 284 to formthe lens 264, as will be explained below.

Busbars 316 can be placed in contact with the spring connectors 304 andcoupled to interconnect assembly 284, details of which will be explainedbelow. The busbars 316 may have a larger cross sectional area, and thusreduced resistivity, along the length of busbars 316 as compared to theother portions of the conductive ink circuit 292 that may utilize higherresistivity in order to generate heat. The busbars 316 may include afirst busbar 316A and a second busbar 316B. Depending on the electricalconfiguration of the interconnect assembly 284, the first busbar 316Acan act as a power busbar with the second busbar 316B acting as a groundor neutral busbar. Alternatively, the first busbar 316A can act as aground or neutral busbar with the second busbar 316B acting as a powerbusbar.

A thermistor 320, which can be a negative temperature coefficient (NTC)resistor, can be coupled to the circuit board 308 and placed in contactwith the lens 264 during manufacturing of the lens 264, which will beexplained in detail below. The thermistor 320 can be used to sense atemperature of the lens 264. The power supplied to the conductive inkcircuit 292 can then be controlled based on the temperature sensed bythe thermistor 320, according to some embodiments.

In some embodiments, a pin connector 324 can be positioned on thecircuit board and coupled to the thermistor 320 and/or the springconnectors 304. The pin connector 324 can have any number of interfaces,such as pins for providing appropriate electrical connections for thecircuit board. For example, four pins can be included to provide a powerconnection, a ground connection, a connection for a first terminal ofthe thermistor 320, and a connection for a second terminal of thethermistor 320, respectively. The power connection and the groundconnection can be used to supply power directly to the conductive inkcircuit 292 or to a regulatory circuit of the circuit board 308 forcontrolling power supplied to the conductive ink circuit 292, which willbe explained below. The connections to the thermistor 320 can be used toprovide a measure of the resistance across the thermistor 320 to anothercircuit board and/or controller. In some embodiments, additional pinscan be provided for other electrical devices that may be coupled to thecircuit board 308 such as optical sensors, additional conductive inkcircuits, or additional thermistors.

In some embodiments, an indicator light 327 can be coupled to thecircuit board 308 and configured to turn on when power is supplied tothe conductive ink circuit 292. As an example, the indicator light 327can be an LED coupled to the conductive ink circuit 292. In someembodiments, the indicator light 327 may be coupled to dedicatedindicator light pins included in the pin connector 324 and controlled byan external circuit and/or controller coupled to the indicator lightpins, and configured to selectively supply power to the indicator lightpins.

According to one non-limiting example embodiment, the lighting system256 was subjected to testing regarding functionality at a range oftemperatures as well as deicing capabilities. The testing procedureincluded placing a thermocouple centered on the outer surface of anouter lens, in this case, the thermoplastic substrate 288. The lightingsystem 256 was then orientated as it would be oriented within a vehicle(e.g., lens 264 placed near an LED light), and with the thermoplasticsubstrate 288 and lens 264 visible through an observation window.Thermocouple measurements and current measurements of currents suppliedto the lighting system were recorded over the duration of the test. Asampling rate of the measurements was high enough to observe thetemperature at which the heater turns on. The lighting system 256 wasplaced in a thermal chamber at 30° C. and powered on high beam and lowbeam at 13.5 VDC. Temperature in the chamber was ramped from 30° C. to−30° C. over a duration of one hour. The temperature in the chamber thenremained at −30° C. for a duration of one hour. The lighting system 256was then subjected to a temperature of −30° C. for one hour while a 2 mmthick layer of ice accumulated on the thermoplastic substrate 288 and/orlens 264 by occasionally applying water to the thermoplastic substrate288 and/or lens 264. The lighting system 256 was then supplied with 13.5VDC with high beam and low beam on. Monitoring of the ice was stoppedwhen the ice on the lighting system 256 exhibited a steady state(defined as no change over 10 minutes), or when the lighting system 256had been powered on for one hour. The lighting system 256 was thenassessed to determine if functionality was maintained after the testing,if all ice had been cleared from the thermoplastic substrate 288 and/orlens 264, and if the lighting system 256 had sustained any damage fromtesting. Here, functionality was maintained, ice was cleared, and thelighting system 256 did not sustain any damage. Accordingly, thelighting system 256 was deemed to pass the testing criteria.

Referring to FIGS. 22-30, a cutaway view of the positioning of thethermoplastic substrate 288 and the interconnect assembly 284 within thelens 264 is shown. An injection molding process can be used to overmoldthe thermoplastic substrate 288 and the interconnect assembly 284 with athermoplastic polymer, such as polycarbonate materials to create thelens 264. An injection molding tool with a cavity and a core can be usedto position the thermoplastic substrate 288 and the interconnectassembly 284. The thermoplastic substrate 288 can be positioned againstthe cavity with the conductive ink circuit 292 facing away from thecavity.

In some embodiments, at least a portion of the interconnect assembly 284can be placed with the spring connectors 304 facing the thermoplasticsubstrate 288 in a pocket of the core. Portions of the interconnectassembly 284 that may be placed in the pocket of the core includeheating connectors 304 and a circuit board 308. The pocket can be sizedto hold the interconnect assembly 284 in place before the resin hascooled and hardened around the interconnect assembly 284. Once the resinhas cooled, the lens 264 can bond to at least a portion of theinterconnect assembly 284 and at least a portion of the thermoplasticsubstrate 288 and hold the interconnect assembly 284 and thethermoplastic substrate 288 in place, forming the lens 264,thermoplastic substrate 288, and the interconnect assembly 284 as asingle piece of construction (i.e. the lens 264 may resist removal ofthe thermoplastic substrate 288 and/or the interconnect assembly 284).In some embodiments, the interconnect assembly 284, spring connectors304, and/or pins 312 may be positioned at least partially within thelens 264.

Forming the lens 264, thermoplastic substrate 288, and the interconnectassembly 284 as a single piece of construction can ease repair of thelighting system 256 such as replacing LEDs. As an example, a user mayonly need to remove the lens 264 and unplug the pin connector 324 fromany attached cables without removing the interconnect assembly 284and/or the thermoplastic substrate 288 from a position in which asuitable electrical connection is made between the pins 312 of theinterconnect assembly 284 and the conductive ink circuit 292 positionedon the thermoplastic substrate 288, thus removing a potentially complexstep of rearranging the interconnect assembly 284 against the conductiveink circuit 292 and/or the thermoplastic substrate 288 in order torecreate the suitable electrical connection, as will be explained below.

According to some embodiments, the core and the interconnect assembly284 can then be moved towards the cavity and the thermoplastic substrate288 until the pins 312 are slightly depressed. In some embodiments, thepins 312 can be depressed by a predetermined amount, such that asufficient electrical connection can be formed. As one example, the pins312 can be depressed by about 10%-30% of a total range of motion of thepins 312, and are in contact with the busbars 316 and/or the conductiveink circuit 292. As described above, thermoplastic polymers, such aspolycarbonate materials, can be utilized as injected resin plasticmaterial to form the lens 264. After the pins 312 have been depressed,the resin plastic material can then be injected into the tool. Theplastic material and/or the lens 264 can overmold at least a portion ofthe conductive ink circuit 292. The plastic material and/or the lens 264can insulate portions of the conductive ink circuit 292 that are not incontact with the spring connectors 304. Once the plastic material hashardened, the lens 264 can hold the spring connectors 304 and theinterconnect assembly 284 in place, i.e. with the pins 312 depressed, toensure the interconnect assembly 284 remains suitably electricallycoupled to the conductive ink circuit 292.

The placement of the interconnect assembly 284 and more specifically thespring connectors 304 against the thermoplastic substrate 288 can beselected in order to ensure that the spring connectors 304 maintain asuitable electrical connection with the conductive ink circuit 292. Ifthe interconnect assembly 284 is positioned too far inward towards thethermoplastic substrate 288, the pins 312 may apply excessive pressureto the conductive ink circuit 292 and potentially break through theconductive ink circuit 292. If the interconnect assembly 284 ispositioned too far away from the thermoplastic substrate 288, the pins312 may not depress far enough and be moved out of contact with theconductive ink circuit 292.

In some scenarios, if the pins 312 are not depressed far enough,injected resin may move the pins 312 out of contact with the conductiveink circuit 292. As described above, the pins may be configured torequire progressively increasing force to be further flexed and/ordepressed as the interconnect assembly 284 is pressed against thethermoplastic substrate 288. The pins 312 may require a relatively lowamount of force to be displaced further when displaced a relativelyshort distance. After the interconnect assembly 284 has been positionedagainst the thermoplastic substrate 288, resin can be injected into theinjection molding tool. The injected resin may press against the pins312 in a sufficient manner to further depress the pins 312 away from thethermoplastic substrate (and thus out of contact with the conductive inkcircuit 292). This can occur if the pins are not depressed far enough,and are biased outwards with an insufficient force to resist furtherdepression from the injected resin.

In some embodiments, the suitable electrical connection between the pins312 and the conductive ink circuit 292 can be a low resistanceconnection. The resistance of the electrical connections is preferablyclose to zero ohms. In some embodiments, a suitable amount of resistancecan be less than about ten percent or less of the resistance of theconductive ink circuit 292.

To determine an appropriate location to position the interconnectassembly 284 against the thermoplastic substrate 288, a thermal cameracan be used to determine if there is a suitable electrical connectionbetween the interconnect assembly 284 and the conductive ink circuit292. The thermal camera can be used to detect heat around areas wherethe pins 312 contact the conductive ink circuit 292. Power can beapplied to the interconnect assembly 284 and the conductive ink circuit292, and if excessive heat is being dispersed around areas where thepins 312 contact the conductive ink circuit 292, the electricalconnection between the interconnect assembly 284 and the conductive inkcircuit 292 may not be efficient. The location of the interconnectassembly 284 against the thermoplastic substrate 288 can be tuned untila threshold of maximum heat being dispersed has been met without causingthe pins 312 to break through the conductive ink.

The thermistor 320 can be over molded by the resin and be placed incontact with the lens 264. The thermistor 320 may then be used to sensea temperature of the lens 264, which may be indicative of a temperatureof the exterior lens side 272 of the lens 264. The temperature indicatedby the resistance of the thermistor 320 may be lower than thesurrounding temperature due to the thickness of the lens 264. Forexample, a resistance value indicative of 20° C. may correspond to atemperature of 5-15° C. at the exterior lens side 272. The difference intemperature can be accounted for via the circuitry powering theconductive ink circuit 292, such that the conductive ink circuit 292provides heat when the temperature of the exterior lens side 272 is lowenough to potentially freeze the exterior lens side 272.

FIG. 31 shows an example process 328 for manufacturing a lens bonded toat least a portion of a thermoplastic substrate and a interconnectassembly. At process step 332, a conductive ink or film circuit can bepositioned on the thermoplastic substrate using a known technique suchas screen printing. In some embodiments, the conductive ink or filmcircuit can include silver traces. Once the conductive ink or filmcircuit has settled, the process 328 can proceed to step 336.

At process step 336, the thermoplastic substrate can be positioned in acavity of an injection molding tool. Specifically, a side of thethermoplastic substrate without the conductive ink or film circuit canbe placed against a wall of the cavity, with the conductive ink or filmcircuit facing away from the cavity. The process can then proceed tostep 340.

At process step 340, a interconnect assembly can be positioned in apocket of a core of the injection molding tool. The interconnectassembly can have one or more spring connectors, each with a pluralityof pins, and a thermistor arranged on side of a circuit board. Theinterconnect assembly can be positioned with the spring connectorsfacing the cavity and more specifically the conductive ink or filmcircuit. The process can then proceed to step 344.

At process step 344, the interconnect assembly can be positioned againstthe thermoplastic substrate to establish a suitable electricalconnection between the interconnect assembly and the thermoplasticsubstrate. Specifically, the connection can be established at theconductive ink or film circuit while closing the injection molding tool.As described above, the placement of the interconnect assembly and morespecifically the spring connectors against the thermoplastic substrate288 can be selected in order to ensure that the spring connectorsmaintain a suitable electrical connection with the conductive inkcircuit. If the interconnect assembly is positioned too far inwardtowards the thermoplastic substrate, the pins may apply excessivepressure to the conductive ink circuit and potentially break through theconductive ink circuit. If the interconnect assembly is positioned toofar away from the thermoplastic substrate, the pins may not depress farenough and be moved out of contact with the conductive ink circuitduring injection of the resin.

As described above, the pins may be configured to require progressivelyincreasing force to be further flexed and/or depressed as theinterconnect assembly is pressed against the thermoplastic substrate.The pins may require a relatively low amount of force to be displacedfurther when displaced a relatively short distance. After theinterconnect assembly has been positioned against the thermoplasticsubstrate, resin can be injected into the injection molding tool. Theinjected resin may press against the pins in a sufficient manner tofurther depress the pins away from the thermoplastic substrate (and thusout of contact with the conductive ink circuit). This can occur if thepins are not depressed far enough, and are biased outwards with aninsufficient force to resist further depression from the injected resin.

In some embodiments, the suitable electrical connection between the pinsand the conductive ink circuit can have a small percentage of theresistance of the conductive ink circuit alone. For example, if theconductive ink circuit has a resistance of two hundred ohms, thesuitable electrical connection may have a resistance of ten ohms, orabout five percent of the total resistance of the conductive inkcircuit. In some embodiments, the suitable electrical connection canhave a resistance of about one percent or less of the resistance of theconductive ink circuit, about two percent or less of the resistance ofthe conductive ink circuit, about five percent or less of the resistanceof the conductive ink circuit, about eight percent or less of theresistance of the conductive ink circuit, or about ten percent or lessof the resistance of the conductive ink circuit 292. Once a suitableelectrical connection has been obtained, the process can proceed to step348.

At process step 348, resin can be injected into the injection moldingtool. The resin can be a thermoplastic polymer. A portion of theinterconnect assembly, a portion of the thermistor and/or a portion ofthe spring connectors can be over molded by the resin. A portion of theinterconnect assembly, a portion of the thermistor and/or a portion ofthe spring connectors can be partially contained within the lens and/orbonded to the lens. A portion of the thermistor can then be placed incontact with the lens that will be formed by the resin. The thermistormay then be used to sense a temperature of the lens, which may beindicative of a temperature of the exterior lens side of the lens. Oncethe resin hardens and forms the lens, the interconnect assembly,thermoplastic substrate, and the lens can form a single piececonstruction component. The process can then proceed to step 352. Atprocess step 352, the single piece component can be removed from theinjection molding tool and placed or utilized in a heated lightingsystem.

Referring to FIG. 32, a circuit diagram of a driver circuit 372 and aheater circuit 376 is shown, according to some embodiments. The drivercircuit 372 can include a temperature difference amplifier 380 and adriver amplifier 384. The temperature difference amplifier 380 can becoupled to a temperature set point voltage supply 388 at a first input392. The temperature set point voltage supply 388 can provide apredetermined voltage that corresponds to a temperature threshold belowwhich the driver circuit 372 will provide power to heater elements 396.The heater elements 396 can include a conductive ink circuit arranged asdescribed above. In some embodiments, the heater elements 396 can be aconductive ink circuit. Power connections for the amplifiers are notshown for simplicity.

The temperature difference amplifier 380 can be coupled to a resistor400 and a thermistor 404 at a second input 408. The resistor 400 can becoupled to a fixed voltage supply 412. The fixed voltage supply 412 canprovide a predetermined voltage that is higher than the voltage suppliedby the temperature set point voltage supply 388.

The thermistor 404 can be a NTC resistor as described above. Thethermistor 404 can generally follow a predetermined resistance v.temperature curve, which can be provided by a manufacturer of thethermistor 404. The thermistor 404 may provide more resistance withdecreasing temperatures. The thermistor 404 can be configured to sense atemperature of a lens of a heated lighting system as described above,such as being arranged to be in contact with an overmolded lens. Asdescribed above, the temperature indicated by the thermistor 404 may bedifferent than the exterior lens temperature. This difference intemperature can be accounted for by selecting appropriate voltages to besupplied by the temperature set point voltage supply 388 and the fixedvoltage supply 412.

The voltage at the second input 408 can vary as the thermistor 404becomes more or less resistive based on temperature. As temperaturesdecrease and the thermistor 404 provides increasingly more resistancethan the resistor 400, less voltage from the fixed voltage supply 412 isdropped across the resistor 400 and the voltage at the second input 408is relatively higher than the voltage at the second input 408 when thethermistor 404 provides less resistance. If the voltage at the secondinput 408 is higher than the voltage at the first input 392 (i.e. thevoltage provided by the temperature set point voltage supply 388), thetemperature difference amplifier 380 can provide a nonzero voltage tothe driver amplifier 384. The driver amplifier 384 can then amplify theprovided voltage and supply power to the heater elements 396. If thevoltage at the second input 408 is lower than the voltage at the firstinput 392, the temperature difference amplifier 380 may provide avoltage of about zero to the driver amplifier 384. The driver amplifier384 may then provide no power to the heater elements 396.

Portions of the driver circuit 372 and the heater circuit 376 may bepositioned at various locations within a lighting system. In someembodiments, both the driver circuit 372 and the heater circuit 376 maybe included in a interconnect assembly such as interconnect assembly 284as described above in conjunction with FIGS. 22-30 above. For example,the driver circuit 372 and the heater circuit 376 can be included in acircuit board such as circuit board 308 as described above inconjunction with FIGS. 22-30. In some embodiments, the heater circuit376 may be included in a interconnect assembly and the driver circuitmay be positioned elsewhere in the lighting system. In some embodiments,the driver circuit 372 may be included in a lighting assembly configuredto power LEDs of the lighting system.

In some embodiments, the fixed voltage supply 412 can be coupled to aswitch such as an electrical switch or electromechanical switch in orderto allow a user or a device such as an electrical device or a mechanicaldevice to control power supplied to the heater elements 396. If thefixed voltage supply 412 is not supplying a voltage to the second input408, the driver circuit 372 may not supply power to the heater elements396. The user or device can then effectively turn the heater on byclosing the switch or off by opening the switch. When the switch isclosed, power can be supplied to the heater elements 396 to be suppliedbased on the resistance of the thermistor 404 and thus a temperature ofthe lens of the lighting system. When the switch is open, power can beprevented from being supplied to the heater elements 396.

Referring to FIG. 33, a box diagram for a heater control system 416 of alighting system is shown, according to some embodiments. The heatercontrol system 416 can include a controller 420 coupled to and incommunication with a speed sensor 424, an optical sensor 428, and atemperature sensor 432. The controller 420 can also be coupled to heaterelements 436 and configured to selectively supply power to the heaterelements. The controller 420 can be positioned within a housing of alighting system. The heater elements 436 can include a conductive inkcircuit positioned on a thermoplastic substrate of a lighting system asdescribed above. The controller 420 can supply power to the heaterelements 436 based on signals received from the speed sensor 424, theoptical sensor 428, and/or the temperature sensor 432, as will bedescribed below.

The controller 420 can receive a temperature value from the temperaturesensor 432. The temperature value can be a signal indicative of atemperature sensed by the temperature sensor 432. The temperature sensor432 can be a thermistor included in a interconnect assembly as describedabove. The controller 420 can supply power to the heater elements 436based on the temperature value. In some embodiments, the controller 420can receive the temperature value, determine the temperature value isbelow a predetermined threshold, and supply a predetermined amount ofpower corresponding to the temperature value to the heater elements 436in response to determining the temperature value is below thepredetermined threshold. The controller 420 may supply more power to theheater elements 436 at lower temperature values. The controller 420 mayhave a plurality of predetermined amounts of power corresponding to aplurality of predetermined thresholds of temperature values in order tobetter supply an appropriate amount of power for a given temperature. Insome embodiments, the controller 420 can input the temperature value toa model configured to output a power amount, receive the power amountfrom the model, and supply power to the heater elements 436 based on thepower amount. The model can include an algorithm for determining powersupplied as a function of temperature values, and can be determinedbased on field testing data of the effectiveness of the lighting systemat various temperatures and amounts of power supplied to the heaterelements 436.

The controller 420 can receive an optical value from the optical sensor428. The optical value can be a signal indicative of light sensed by theoptical sensor 428. The optical sensor 428 can be positioned in thelighting system in order to determine about how much light is shiningthrough a lens and/or thermoplastic substrate of the lighting system.Low optical values may indicate that the lighting system has at leastpartially frozen over or is otherwise occluded by sleet, ice, snow, etc.If the optical value is below a predetermined threshold, the controller420 can supply power to the heater elements 436. In some embodiments,the controller 420 can receive the optical value, determine the opticalvalue is below a predetermined threshold, and supply a predeterminedamount of power corresponding to the optical value to the heaterelements 436 in response to determining the optical value is below thepredetermined threshold. The controller 420 may supply more power to theheater elements 436 at lower optical values. The controller 420 may havea plurality of predetermined amounts of power corresponding to aplurality of predetermined thresholds of optical values in order tobetter supply an appropriate amount of power for a given optical value.In some embodiments, the controller 420 can input the optical value to amodel configured to output a power amount, receive the power amount fromthe model, and supply power to the heater elements 436 based on thepower amount. The model can include an algorithm for determining powersupplied as a function of optical values, and can be determined based onfield testing data of the effectiveness of the lighting system atvarious levels of occlusion corresponding to sensed optical values andamounts of power supplied to the heater elements 436.

The controller 420 can receive a speed value from the speed sensor 424.In some embodiments, the speed sensor 424 can be a speedometer coupledto the vehicle that the lighting system is coupled to. The speed valuecan be a signal indicative of a speed sensed by the speed sensor 424. Atspeed values associated with relatively high speed, for example highwayspeeds, it may be necessary to provide more power to the heater elements436 due to sleet, snow, and/or ice accumulating on the lighting systemmore rapidly than at relatively low speeds. If the speed value is abovea predetermined threshold, the controller 420 can supply power to theheater elements 436. In some embodiments, the controller 420 can receivethe speed value, determine the speed value is above a predeterminedthreshold, and supply a predetermined amount of power corresponding tothe speed value to the heater elements 436 in response to determiningthe speed value is above the predetermined threshold. The controller 420may supply more power to the heater elements 436 at higher speed values.The controller 420 may have a plurality of predetermined amounts ofpower corresponding to a plurality of predetermined thresholds of speedvalues in order to better supply an appropriate amount of power for agiven speed value. In some embodiments, the controller 420 can input thespeed value to a model configured to output a power amount, receive thepower amount from the model, and supply power to the heater elements 436based on the power amount. The model can include an algorithm fordetermining power supplied as a function of speed values, and can bedetermined based on field testing data of the effectiveness of thelighting system at various speeds corresponding to sensed speed valuesand amounts of power supplied to the heater elements 436. In this way,an appropriate amount of power to be supplied at a given speed can bedetermined.

In some embodiments, the controller 420 can supply power to the heaterelements 436 based on a combination of a received speed value, opticalvalue, and/or temperature value. For example, the controller 420 canhave a stored lookup table of power values, each power valuecorresponding to a predetermined speed value, optical value, and/ortemperature value. Using a combination of a received speed value,optical value, and/or temperature value to determine the power outputcan allow the controller 420 to provide a more appropriate level ofpower to the heater elements 436 than if a single value was used.

The controller 420 can be coupled to a switch 440. The controller 420can receive a wired input value from the switch 440, which can allow auser or a device such as an electrical device or a mechanical device toinput commands to the controller 420. The wired input value can be usedto determine how much power is supplied to the heater elements 436. Thewired input value can have a range of values based on the constructionof the switch 440. For example, the switch 440 can supply an “on” valueand an “off” value if the switch is a two position selector switch or arelay. Alternatively, the switch 440 can supply an “off” value, a firstposition value, and a position level value if the switch is a threeposition selector switch. Further, a continuous range of values may besupplied if the switch is a potentiometer. Other ranges of valuescorresponding to a range of power values can be supplied to the heaterelements 436. The controller 420 can supply a predetermined amount ofpower corresponding to the position of the switch 440, i.e. an amountfor an “on” value, a first position value, and/or a second positionvalue. If the switch 440 can supply a continuous range of values, thecontroller 420 can receive a wired input value, determine that the wiredinput value is indicative of a switch position value such as an “on”value, a first position value, or second position value, and supply apredetermined amount of power corresponding to the switch position valueto the heater elements 436.

In some embodiments, the controller 420 can be coupled to and incommunication with a wireless module 444. The controller 420 can receivea wireless input value from the wireless module 444, which can be atransceiver capable of one or two-way communication using one or morewireless protocols including but not limited to Bluetooth, WiFi, Zigbee,or other appropriate wireless communication protocols. The wirelessinput value can be sent from an electrical device that may be externalto the lighting system, such as a smartphone or a control FOB. Thesmartphone can be configured to run an application capable of receivinguser input from an interface and sending an appropriate wireless inputvalue based on the user input. In some embodiments, the wireless module444 can be included in the controller 420. The controller 420 canreceive a wireless input value, determine the wireless input value isindicative of a power level to be supplied to the heater elements 436such as an “on” value corresponding to a fixed predetermined power levelor one of a range of power values such as a first power value and orsecond power value, and supply a predetermined amount of powercorresponding to the power level to the heater elements 436.

Referring to FIGS. 34 and 35, an additional embodiment of a lightingsystem 448 is shown. The lighting system 448 can include a base 452 anda lens 462. At least one LED 456 can be positioned within the base 452to provide illumination through the lens 462. A conductive ink or filmcircuit 460 can be positioned on an interior side of a thermoplasticsubstrate 466. The thermoplastic substrate 466 can be positioned on anexterior side of the lens 462, with the conductive ink circuit 460facing the lens 462. A interconnect assembly 468 can be at leastpartially over molded by the lens 462 as described above, and beelectrically coupled to the conductive ink circuit 460. The lens 462 canbe bonded to at least a portion of the thermoplastic substrate 466 andthe interconnect assembly 468. In some embodiments, the lens 462, thethermoplastic substrate 466, and the interconnect assembly 468 may forma single piece of construction. The interconnect assembly 468 may havespring connectors as described above for contacting the conductive inkcircuit 460 and providing a suitable electrical connection for poweringthe conductive ink circuit 460 and thus heating the lens 462. Theinterconnect assembly may include and/or be coupled to portions of adriver circuit as described above and a heater circuit as describedabove, or be coupled to a controller configured to selectively power theconductive ink circuit 460 as described above.

Busbars 464 can be placed in contact with the spring connectors andcoupled to interconnect assembly 468. The busbars 464 may have a largercross sectional area, and thus reduced resistivity, along the length ofbusbars 464 as compared to the other portions of the conductive inkcircuit 460 that may utilize higher resistivity in order to generateheat. The busbars 464 may include a first busbar 464 a and a secondbusbar 464 b. Depending on the electrical configuration of theinterconnect assembly 468, the first busbar 464 a can act as a powerbusbar with the second busbar 464 b acting as a ground or neutralbusbar. Alternatively, the first busbar 464 a can act as a ground orneutral busbar with the second busbar 464 b acting as a power busbar.

Referring to FIGS. 36-39, various components of another embodiment of alighting system 472 are shown. The lighting system 472 can include abase 476 and a lens 500. At least one LED 497 can be positioned withinthe base 476 to provide illumination through the lens 500. A conductiveink or film circuit 480 can be positioned on an interior side of athermoplastic substrate 496. The thermoplastic substrate 496 positionedon an exterior side of the lens 500, with the conductive ink circuit 480facing the lens 500. The conductive ink circuit 480 can include multiplebus bars 484, each of which may be a power busbar or a neutral or groundbusbar. A interconnect assembly 488 can be at least partially overmolded by the lens 500 as described above, and be electrically coupledto the conductive ink circuit 480. The lens 500 can be bonded to atleast a portion of the thermoplastic substrate 496 and the interconnectassembly 488, and the lens 500, the thermoplastic substrate 496, and theinterconnect assembly 488 may form a single piece of construction. Theinterconnect assembly 488 may have spring connectors as described abovefor contacting the conductive ink circuit 480 and providing a suitableelectrical connection for powering the conductive ink circuit 480 andthus heating the lens 500. The interconnect assembly may include and/orbe coupled to portions of a driver circuit as described above and aheater circuit as described above, or be coupled to a controllerconfigured to selectively power the conductive ink circuit 480 asdescribed above. The lighting system 472 may power the conductive inkcircuit 480 at a rate of about two watts per square inch, which mayallow the lighting system 472 to be used in relatively high speedapplications such as mounted on a snowplow that operates at highwayspeeds.

According to one non-limiting example embodiment, the lighting system472 was subjected to testing regarding functionality at a range oftemperatures as well as deicing capabilities. The testing procedureincluded placing a thermocouple centered on the outer surface of anouter lens, in this case, the thermoplastic substrate 496. The lightingsystem 472 was then orientated as it would be oriented within a vehicle(e.g., lens 500 placed near an LED light), and with the thermoplasticsubstrate 496 and lens 500 visible through an observation window.Thermocouple measurements and current measurements of currents suppliedto the lighting system were recorded over the duration of the test. Asampling rate of the measurements was high enough to observe thetemperature at which the heater turns on. The lighting system 472 wasplaced in a thermal chamber at 30° C. and powered on high beam and lowbeam at 13.5 VDC. Temperature in the chamber was ramped from 30° C. to−30° C. over a duration of one hour. The temperature in the chamber thenremained at −30° C. for a duration of one hour. The lighting system 472was then subjected to a temperature of −30° C. for one hour while a 2 mmthick layer of ice accumulated on the thermoplastic substrate 496 and/orlens 500 by occasionally applying water to the thermoplastic substrate496 and/or lens 500. The lighting system 472 was then supplied with 13.5VDC with high beam and low beam on. Monitoring of the ice was stoppedwhen the ice on the lighting system 472 exhibited a steady state(defined as no change over 10 minutes), or when the lighting system 472had been powered on for one hour. The lighting system 472 was thenassessed to determine if functionality was maintained after the testing,if all ice had been cleared from the thermoplastic substrate 496 and/orlens 500, and if the lighting system 472 had sustained any damage fromtesting. Here, functionality was maintained, ice was cleared, and thelighting system 472 did not sustain any damage. Accordingly, thelighting system 472 was deemed to pass the testing criteria.

Referring to FIGS. 40-46, components of yet another embodiment of alighting system 504 are shown. The lighting system 504 can include abase 508 and a lens 532. At least one LED 529 can be positioned withinthe base 508 to provide illumination through the lens 532. A lightingassembly 520 can be configured to provide power to the at least one LED529. A conductive ink or film circuit 516 can be positioned on aninterior side of a thermoplastic substrate 528. The thermoplasticsubstrate 528 can be positioned on an exterior side of the lens 532,with the conductive ink circuit 516 facing the lens 532. The conductiveink circuit 516 can include multiple bus bars 544, each of which may bea power busbar or a neutral or ground busbar. A interconnect assembly524 can be at least partially over molded by the lens 532 as describedabove, and be electrically coupled to the conductive ink circuit 516.The interconnect assembly 524 can include a spring connector 536 withone or more pins 540. The pins of each spring connector 536 can bepositioned to be in contact with one of the bus bars 544. The lens 532can be bonded to at least a portion of the thermoplastic substrate 528and the interconnect assembly 524. In some embodiments, the lens 532,the thermoplastic substrate 528, and the interconnect assembly 524 mayform a single piece of construction. The interconnect assembly 524 mayhave spring connectors as described above for contacting the conductiveink circuit 516 and providing a suitable electrical connection forpowering the conductive ink circuit 516 and thus heating the lens 532.The interconnect assembly may include and/or be coupled to portions of adriver circuit as described above and a heater circuit as describedabove, or be coupled to a controller configured to selectively power theconductive ink circuit 516 as described above.

According to one non-limiting example embodiment, the lighting system504 was subjected to testing regarding functionality at a range oftemperatures as well as deicing capabilities. The testing procedureincluded placing a thermocouple centered on the outer surface of anouter lens, in this case, the thermoplastic substrate 528. The lightingsystem 504 was then orientated as it would be oriented within a vehicle(e.g., lens 532 placed near an LED light), and with the thermoplasticsubstrate 528 and lens 532 visible through an observation window.Thermocouple measurements and current measurements of currents suppliedto the lighting system were recorded over the duration of the test. Asampling rate of the measurements was high enough to observe thetemperature at which the heater turned on. The lighting system 504 wasplaced in a thermal chamber at 30° C. and powered on high beam and lowbeam at 13.5 VDC. Temperature in the chamber was ramped from 30° C. to−30° C. over a duration of one hour. The temperature in the chamber thenremained at −30° C. for a duration of one hour. The lighting system 504was then subjected to a temperature of −30° C. for one hour while a 2 mmthick layer of ice accumulated on the thermoplastic substrate 528 and/orlens 532 by occasionally applying water to the thermoplastic substrate528 and/or lens 532. The lighting system 504 was then supplied with 13.5VDC with high beam and low beam on. Monitoring of ice was stopped whenthe ice on the lighting system 504 exhibited a steady state (as definedas no change over 10 minutes), or when the lighting system 504 had beenpowered on for one hour. The lighting system 504 was then assessed todetermine if functionality was maintained after the testing, if all icehad been cleared from the thermoplastic substrate 528 and/or lens 532,and if the lighting system 504 had sustained any damage from testing.Here, functionality was maintained, ice was cleared, and the lightingsystem 504 did not sustain any damage. Accordingly, the lighting system504 was deemed to pass the testing criteria.

Referring to FIGS. 47-48, various components of another embodiment of alighting system 548 are shown. The lighting system 548 can include abase 552 and a lens 553. At least one LED 556 can be positioned withinthe base 552 to provide illumination through the lens 553. A conductiveink or film circuit 560 can be positioned on an interior side of athermoplastic substrate. The thermoplastic substrate positioned on anexterior side of the lens 553, with the conductive ink circuit 560facing the lens 553. The conductive ink circuit 560 can include multiplebusbars 564. Busbars 564B and 564C may be a power busbar or a neutral orground busbar respectively. Busbar 564C can be a bridge busbarconfigured to provide a low resistance electrical connection betweenbusbars 564B and 564C. A interconnect assembly 568 can be at leastpartially over molded by the lens 553 as described above, and beelectrically coupled to the conductive ink circuit 560. The lens 553 canbe bonded to at least a portion of the thermoplastic substrate and theinterconnect assembly 568, and the lens 553, the thermoplasticsubstrate, and the interconnect assembly 568 may form a single piece ofconstruction. The interconnect assembly 568 may have spring connectorsas described above for contacting the conductive ink circuit 560 andproviding a suitable electrical connection for powering the conductiveink circuit 560 and thus heating the lens 553. The interconnect assemblymay include and/or be coupled to portions of a driver circuit asdescribed above and a heater circuit as described above, or be coupledto a controller configured to selectively power the conductive inkcircuit 560 as described above.

It is to be appreciated that the heated lighting assemblies presented inthis disclosure can be used for a variety of applications in whichheated lighting assemblies may perform better than non-heated lightingassemblies such as applications with vehicles operating in coldtemperatures (e.g., snow plows, helicopters, snowmobiles, semi-trucks,freight and passenger trains, airplanes, ice resurfacers, etc.),applications with refrigeration systems that require lighting (e.g.,industrial freezers, warehouses, lab equipment, etc.), applications withoutdoor lighting in cold environments (e.g., construction sites, oildrilling platforms, various water vessels, streetlamps, heavy dutyflashlights, etc.), and other lens applications associated with lowtemperature environments.

The present disclosure describes embodiments with reference to theFigures, in which like numbers represent the same or similar elements.Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

The described features, structures, or characteristics of theembodiments may be combined in any suitable manner in one or moreembodiments. In the description, numerous specific details are recitedto provide a thorough understanding of embodiments of the invention. Oneskilled in the relevant art will recognize, however, that theembodiments may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of theinvention. Accordingly, the scope of the technology should be determinedfrom the following claims and not be limited by the above disclosure.

The invention claimed is:
 1. A lens heating system comprising: asubstantially clear thermoplastic substrate; a conductive ink or filmcircuit, positioned on the thermoplastic substrate to heat thethermoplastic substrate; a lens heater circuit including a circuit boardand a lens heater, operatively coupled to a lens heater controller, thecontroller configured to: determine a temperature associated with anouter lens surface; and activate the lens heater in response to adetermination that the temperature is less than or equal to a thresholdtemperature; and a spring connector comprising a plurality of pins, thepins configured to couple to the conductive ink or film circuit, thepins further configured to provide an electrical connection between thepins and the conductive ink or film circuit, and the spring connectorbeing surface-mounted to the circuit board.
 2. The system of claim 1,wherein the controller is coupled to a thermistor, the thermistorconfigured to determine the temperature associated with the outer lenssurface.
 3. The system of claim 2, wherein the thermistor is a negativetemperature coefficient (NTC) thermistor.
 4. The system of claim 1,wherein the spring connectors are positioned at least partially within alens coupled to the substantially clear thermoplastic substrate.
 5. Thesystem of claim 1, further comprising a second spring connector coupledto a second busbar of the conductive ink or film circuit, and whereinthe spring connector is coupled to a first busbar of the conductive inkor film circuit.
 6. A method for heating a lens of a lighting system,the method comprising: applying a conductive ink or film circuit on asubstantially clear thermoplastic substrate; applying the conductive inkor film circuit on the substantially clear thermoplastic substrate to atleast one of an interior lens side and an exterior lens side;positioning a spring connector comprising a plurality of pins againstthe conductive ink or film circuit, and establishing an electricalconnection between the pins and the conductive ink or film circuit;positioning the spring connector at least partially within the lenscoupled to the substantially clear thermoplastic substrate; and applyinga controlled power to the conductive ink or film circuit to heat thelens.
 7. The method of claim 6, wherein the positioning comprises:moving the spring connector towards the conductive ink or film circuituntil the pins have flexed a predetermined amount corresponding toestablishing the electrical connection.
 8. The method of claim 6 furthercomprising: receiving a value from a wireless module; and supplyingpower to the conductive ink or film circuit based on the value.
 9. Themethod of claim 6 further comprising: receiving a value from a speedsensor; determining the speed value is above a predetermined threshold;and supplying, in response to determining the speed value is above thepredetermined threshold, a predetermined amount of power to theconductive ink or film circuit.
 10. The method of claim 6 furthercomprising: receiving a value from an optical sensor; determining theoptical value is below a predetermined threshold; and supplying, inresponse to determining the optical value is below the predeterminedthreshold, a predetermined amount of power to the conductive ink or filmcircuit.
 11. A heated lighting system comprising: a substantially clearthermoplastic substrate; a conductive ink or film circuit, positioned onthe thermoplastic substrate to heat the thermoplastic substrate; a lensin contact with the thermoplastic substrate; and a interconnect assemblyincluding a plurality of spring connectors, the spring connectorspositioned in contact with the conductive ink or film circuit, and theinterconnect assembly positioned at least partially within the lens. 12.The system of claim 11, wherein the interconnect assembly is configuredto supply power to the conductive ink or film circuit.
 13. The system ofclaim 11, wherein the lens is bonded to at least a portion of theinterconnect assembly and at least a portion of the thermoplasticsubstrate.
 14. The system of claim 11, wherein the conductive ink orfilm circuit is positioned on an exterior surface of the lens.
 15. Thesystem of claim 11, wherein the lens is constructed from a thermoplasticpolymer.
 16. A lens heating system comprising: a substantially clearthermoplastic substrate; a conductive ink or film circuit, positioned onthe thermoplastic substrate to heat the thermoplastic substrate; a lensheater circuit including a lens heater operatively coupled to a lensheater controller, the controller configured to: determine a temperatureassociated with an outer lens surface; and activate the lens heater inresponse to a determination that the temperature is less than or equalto a threshold temperature; and a spring connector comprising aplurality of pins, the pins configured to couple to the conductive inkor film circuit, the pins further configured to provide an electricalconnection between the pins and the conductive ink or film circuit,wherein the spring connector is positioned at least partially within alens coupled to the substantially clear thermoplastic substrate.
 17. Thesystem of claim 16, wherein the controller is coupled to a thermistor,the thermistor configured to determine the temperature associated withthe outer lens surface.
 18. The system of claim 17, wherein thethermistor is a negative temperature coefficient (NTC) thermistor. 19.The system of claim 16, further comprising a second spring connectorcoupled to a second busbar of the conductive ink or film circuit, andwherein the spring connector is coupled to a first busbar of theconductive ink or film circuit.
 20. The system of claim 16, wherein thelens heater circuit further comprises a circuit board, the springconnector being surface-mounted to the circuit board.
 21. A lens heatingsystem comprising: a substantially clear thermoplastic substrate; aconductive ink or film circuit, positioned on the thermoplasticsubstrate to heat the thermoplastic substrate; a spring connectorcomprising a plurality of pins, the pins configured to couple to theconductive ink or film circuit, the pins further configured to providean electrical connection between the pins and the conductive ink or filmcircuit; and a lens heater circuit including a lens heater operativelycoupled to a lens heater controller, the controller configured to:determine a temperature associated with an outer lens surface; activatethe lens heater in response to a determination that the temperature isless than or equal to a threshold temperature; receive at least onesensor value from at least one of a speed sensor and an optical sensor;determine the at least one sensor value is below a predeterminedthreshold; and supply, in response to determining the at least onesensor value is below the predetermined threshold, a predeterminedamount of power to the conductive ink or film circuit.